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arXiv · 1504.01465

Thermal conductivity of IPA-CuCl_3: Evidences of ballistic magnon transport and limited applicability of the Bose-Einstein condensation model

Z. Y. Zhao·B. Tong·X. Zhao·L. M. Chen·J. Shi·F. B. Zhang·J. D. Song·S. J. Li·J. C. Wu·H. S. Xu·X. G. Liu·X. F. Sun
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Abstract

The heat transport of the spin-gapped material (CH_3)_2CHNH_3CuCl_3 (IPA-CuCl_3), a candidate quantum magnet with Bose-Einstein condensation (BEC), is studied at ultra-low temperatures and in high magnetic fields. Due to the presence of the spin gap, the zero-field thermal conductivity (κ) is purely phononic and shows a ballistic behavior at T < 1 K. When the gap is closed by magnetic field at H = H_{c1}, where a long-range antiferromanetic (AF) order of Cu^{2+} moments is developed, the magnons contribute significantly to heat transport and exhibit a ballistic T^3 behavior at T < 600 mK. In addition, the low-T κ(H) isotherms show sharp peaks at H_{c1}, which indicates a gap re-opening in the AF state (H > H_{c1}) and demonstrates limited applicability of the BEC model to IPA-CuCl_3.

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Z. Y. Zhao, B. Tong, X. Zhao, L. M. Chen, J. Shi, F. B. Zhang, J. D. Song, S. J. Li, J. C. Wu, H. S. Xu, X. G. Liu, X. F. Sun. 2015-04-07. Thermal conductivity of IPA-CuCl_3: Evidences of ballistic magnon transport and limited applicability of the Bose-Einstein condensation model. https://doi.org/10.1103/physrevb.91.134420

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